The present invention relates to a magnetically actuated float switch which is actuated in response to a changing fluid level, particularly a magnetically actuated float switch which utilizes a float rod magnet that may be interposed between two repellingly arranged magnetic bodies and the resulting magnetic interaction results in the actuation of a switch. The present magnetically actuated float switch is capable of being operably connected to a electric load device such as a pump.
Liquid level sensing float switches have been in use for some time. These switches have been commonly used in conjunction with pumps or other electrical load devices, such as alarms, solenoid valves, semiconductor devices and the like. When used in connection with pumps, the switches are typically used to detect a desired liquid level, and when the desired level is reached or exceeded the switch actuates and subsequently activates the pump, which functions to displace the liquid until the level falls below the desired level. In such embodiments the liquid level is typically detected by a float which is freely moveable about and along a support member or rod, with the float controlling the actuation of a switch element as it moves up and down vertically along the float rod in response to the liquid level. When liquid level rises above a set point the switch will actuate in a first manner, and when the liquid level falls below a set point the switch will actuate in a second manner.
It will be appreciated by those skilled in the art that a wide variety of float switches exist, and that numerous float switches employ magnets. It will also be appreciated that known float switches often have multiple and differing functions.
U.S. Pat. No. 4,836,239 to Kinkead entitled "Water Cooling Tower And Water Level Control System Therefor" employs two magnets which are oriented in a repelling arrangement so that a substantial additional force is required to move the distal end of a lever arm. This type of arrangement does not provide a uniform switching action which is reliable for many cycles.
U.S. Pat. No. 4,943,210 to Bailey, Jr. et al entitled "Pump Control System, Level Sensor Switch and Switch Housing" utilizes a fluid pump, a partially hollow cylindrical float buoy which is disposed about a stem, and a reed switch. The stem is conductively connected to a pump. Within the stem, at a predetermined level is a normally open reed switch. Within the float buoy is a ring shaped magnet that surrounds the stem. As the float buoy rises with the liquid level, the magnetic nature of the ring magnet causes the reeds in the switch to be repelled away from the magnet thus forcing the reeds together. The mutual contact of the reeds closes the switch and activates a timer. This type of arrangement does not provide a uniform switching action and is not well suited to high vibration pump applications.
Another example of a float switch using magnets is U.S. Pat. No. 5,030,803 to Yarbrough, entitled "Offset Float Switch". Yarbrough provides for a switch that may be actuated by two floats, within the floats are switching magnets which allow the switch to be actuated when fluid level drops to a first level and actuated to a second position when the liquid rises to a second level which is above the first level. Like Bailey Jr. et al., Yarbrough utilizes a central stem with the floats disposed thereabout, and a reed switch within the stem. This type of arrangement does not provide a uniform switching action and is not well suited to high vibration pump applications.
U.S. Pat. No. 5,141,404 to Newcomer et al, entitled "Pump Apparatus" utilizes magnets arranged in a repelling arrangement to actuate a pump. The arrangement disclosed here does not provide a uniform switching action.
U.S. Pat. No. 5,562,422 to Ganzon et al, entitled "Liquid Level Control Assembly For Pumps" is directed to apparatus which uses magnets in an attracting arrangement to actuate a pump. The arrangement disclosed here does not provide a uniform switching action.
In light of the shortcomings described above what is needed is a switch which is magnetically actuated, reliable for many cycles and which provides a more uniform and consistent switching action.
It is a further goal to provide a magnetically actuated float switch to be utilized separately or within the existing housing of an electrical load device such as a pump.